[PATCH v2 5/9] KVM: s390: Fix pgste_get_trylock_multiple()

[Claudio Imbrenda <imbrenda@linux.ibm.com>]

In case of failure, pgste_get_trylock_multiple() will attempt to unlock
the locked PGSTEs based on whether the PCL is set. In some
circumstances this can lead to unlocking PGSTEs that were locked by
other threads.

Fix by unlocking the amount of PGSTEs that were actually locked,
ignoring the PCL bit in the array.

Fixes: 94fd9b16cc67 ("KVM: s390: KVM page table management functions: lifecycle management")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
---
 arch/s390/kvm/dat.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/arch/s390/kvm/dat.c b/arch/s390/kvm/dat.c
index 165c704fcf29..f4dd6f783417 100644
--- a/arch/s390/kvm/dat.c
+++ b/arch/s390/kvm/dat.c
@@ -923,11 +923,8 @@ static void pgste_set_unlock_multiple(union pte *first, int n, union pgste *pgst
 {
 	int i;
 
-	for (i = 0; i < n; i++) {
-		if (!pgstes[i].pcl)
-			break;
+	for (i = 0; i < n; i++)
 		pgste_set_unlock(first + i, pgstes[i]);
-	}
 }
 
 static bool pgste_get_trylock_multiple(union pte *first, int n, union pgste *pgstes)
@@ -940,7 +937,7 @@ static bool pgste_get_trylock_multiple(union pte *first, int n, union pgste *pgs
 	}
 	if (i == n)
 		return true;
-	pgste_set_unlock_multiple(first, n, pgstes);
+	pgste_set_unlock_multiple(first, i, pgstes);
 	return false;
 }
 
-- 
2.55.0